The number of pending watchers.
0
indicates that there are no watchers pending.

io_interval

Higher
io_interval
allows
libev
to spend more time collecting
EvIo
events, so more events can be handled per iteration, at the cost of
increasing latency. Timeouts (both
EvPeriodic
and
EvTimer
) will not be affected. Setting this to a non-zero value will introduce
an additional
sleep()
call into most loop iterations. The sleep time ensures that
libev
will not poll for
EvIo
events more often than once per this interval, on average. Many
programs can usually benefit by setting the
io_interval
to a value near
0.1
, which is often enough for interactive servers(not for games). It
usually doesn't make much sense to set it to a lower value than
0.01
, as this approaches the timing granularity of most systems.

Higher
timeout_interval
allows
libev
to spend more time collecting timeouts, at the expense of increased
latency/jitter/inexactness(the watcher callback will be called later).
EvIo
watchers will not be affected. Setting this to a non-null value will
not introduce any overhead in
libev
. See also
» FUNCTIONS
CONTROLLING EVENT LOOPS
.